Glossary term:

Subarachnoid channels

Cerebrospinal fluid forms, for the most part, within the ventricles of the brain. From there it flows out, at the base of the brain, and on over the surface of the brain, then to be re- absorbed back into the bloodstream, mainly into the superior sagittal sinus. Some also flows into the spinal canal. The ventricles and other courses along which the cerebrospinal fluid flows, inside the head and the spinal canal, make up the subarachnoid channels. The term subarachnoid space is commonly used, arguably in error as it implies that these channels are empty, whereas they are, in life, “flooded” with cerebrospinal fluid.